This would be similar to the "Color gradient" option, but rather than cycle the colors across the led strip the colors would cycle across the entire strip within the specified spectrum all as one.
Like in this video at 1:18
https://youtu.be/PBzVeo2bQBo
and you could specify the colors, how many steps and the speed of the cycling.
Maybe a checkbox in
"Color gradient" that would say all LEDs at once or something like that.
Also shown in this video at 7:40
https://youtu.be/tkfengnRF9c
Actually "Color switch" with the fade option turned on is close but rather than sensor driven it would cycle at some user specified speed